1. Field of the Invention
This invention generally relates to an arrangement for, and a method of, discriminating an information signal from a background signal, and, more particularly, to automatically discriminating incident infrared light radiation from ambient light and temperature fluctuations in an optical receiver system for detecting the presence of an animate or inanimate object.
2. Description of the Related Art
There are many applications in which a sensor detects incident radiation, such as infrared light, and generates useful information signals therefrom. However, the sensor is sensitive not only to the incident radiation, but also to ambient light and temperature fluctuations whose detection leads to file generation of undesirable background noise signals. To obtain useful data, the background signals are removed from the information signals.
The following U.S. Pat. Nos. are exemplificative of known systems for removing background signals: 3,430,047; 3,657,644; 3,751,667; 3,777,568; 3,867,628; 4,061,925; 4,128,760; 4,115,006; 4,198,602; 4,303,855; 4,536,666; 4,570,075; 4,733,398; 4,792,682; 4,945,225; 5,039,952; and 5,073,760.
It will be seen that the known ambient light compensating circuitry is fairly complex and costly and, in many cases, impractical. The need persists for a relatively simple, reliable, inexpensive arrangement for discriminating between a radiation information signal and a background signal, especially over a wide dynamic range, and over variable environmental conditions.